Insult rap star 50 Cent and four members of his entourage spent New Year’s Eve cooling their heels in custody after they were busted outside the Copacabana with two loaded guns and a rack full of bulletproof vests in an armor-plated SUV, authorities said.

The 27-year-old Queens rapper, whose real name is Curtis Jackson, was about to perform in front of hundreds of hip-hop fans when an officer noticed a .25-caliber gun underneath his car seat, cops said.

Cops said they later also found a .45-caliber gun inside the tank-like 2001 Jeep.

“I’m having a bad day,” a cocky 50 Cent told The Post as he was transferred to Central Booking.

Jackson did not comment after being released on $10,000 bail last night.

Eliezer Cortez, 35, of Brooklyn, Timothy Bonaparte, 27, of Connecticut, and Christopher Lloyd, 20 and Jean Bernard, 26, both of Queens, were charged, along with Jackson, with weapons possession.

Jackson surfaced as a potential target for violence after the Oct. 30 execution-style shooting of his mentor, Jam Master Jay, whose real name was Jason Mizell.

Immediately after the killing, investigators learned of a threat to 50 Cent and, at their suggestion, he canceled a performance. Police later downplayed any suggestion that Jam Master Jay’s killers were after him, but hip-hop insiders have speculated the killing may have been prompted by 50 Cent’s recorded taunts.

Police said they had established a so-called “hip-hop squad,” an offshoot of the NYPD’s Gang Intelligence Unit, to investigate violence in the rap world, but sources said 50 Cent had turned down their offer of protection.

The outspoken former boxer is well-known for his taunting rhymes in which he ridicules rival rappers such as Jay-Z and Ja Rule.